Stuttering is a disorder of speech with a prevalence estimated to be 1% of the world's population. It is often a significant communicative problem for the individual, limiting educational and employment opportunities and social and psychological adjustment. The etiology of stuttering is unknown, and treatment strategies and outcomes are highly variable. A major impediment to understanding the etiology of stuttering and to the development of successful therapeutic techniques is the lack of understanding of the physiological bases of the disorder. Stuttering manifests itself as a breakdown in speech motor processes. The complex factors known to affect the occurrence of stuttering, including psychosocial, cognitive, and linguistic variables, must ultimately have an effect on the physiological events necessary for the production of speech. Therefore, to understand stuttering it is essential to understand the physiological mechanisms underlying disruptions of speech motor processes in stuttering. The experiments proposed in this application addresses the role of linguistic processing in stuttering by taking a new approach, one that focuses on the neurophysiology of the perception and the production of linguistic stimuli. Averaged electrical responses of the brain to linguistic stimuli will be used to explore the linguistic processing abilities of children and adults who stutter. These experiments will determine if people who stutter have atypical neural subsystems for language even when they are only listening to words and not producing them. In another set of experiments the same participants will produce utterances that are designed to challenge linguistic planning and production processes for speech. The results of these experiments will provide major progress toward understanding the multiple factors that influence stuttering in children and adults.